The spread of zebra mussels in the North America, especially the United States, has been extraordinary. Because of their unique ability to attach to boats, they quickly spread throughout the Great Lakes and eventually into a large portion of the Mississippi River drainage. It is commonly accepted that large barges spread them up and down the large navigable waterways such as the Mississippi, Ohio, Tennessee, and Arkansas rivers their first few years here. In 2007, zebra and quagga mussels were discovered west of the Rocky Mountains for the first time. Lake Mead in Nevada was the initial place of discovery. The quagga mussel population was very large in the lake and had gone undetected for an unknown number of years. Since then, either zebra or quagga mussels have been found in Arizona, California, Colorado, Texas, and Utah. In the eastern United States, both species continue to disperse into small lakes in the Great Lakes region and into states such as Maryland and Massachusetts where no populations had existed. To see if there are zebra mussels in a lake near you, go to our Distribution in Small Lakes map. Photo Gallery

PROGRESSION OF ZEBRA MUSSEL (Dreissena polymorpha) AND QUAGGA MUSSEL (D. rostriformis bugensis) DISTRIBUTIONS IN NORTH AMERICAmouse-over years to displayNote: images may be loading in the background

2010 - Zebra mussels were found in two additional lakes in Connecticut and in a second Nebraska lake.

2009 - New populations of zebra mussels were discovered for the first time in Texas and Massachusetts. Quagga mussels were detected in Utah.

2008 - Zebra mussels were discovered for the first time in California and in Utah. Both species were discovered in Colorado.

2007 - Quagga mussels were discovered in Lake Mead, Nevada, the first population west of the Continental Divide. Downstream from Lake Mead, mussels were found in the Colorado River in California and Arizona.

2006 - Quagga mussels were found in western Pennsylvania quarry.

2005 - Zebra mussels were detected for the first time in 15 new lakes in Michigan.

2004 - Zebra mussels were found in a second reservoir in Kansas.

2003 - Zebra mussels were discovered for the first time in Kansas at El Dorado Lake, a reservoir on the Walnut River. Larvae, also called veligers, were collected late in the year in the Missouri River just above and below Lewis and Clark Lake.

2002 - The state of Virginia was added to the list of states with zebra mussels when a population was discovered in an isolated rock quarry.

2001 - More small lakes infestations occurring in the Great Lakes states.

2000 - The known spread of zebra mussels to new habitats is occurring almost exclusively in small lakes which are in close proximity to other infested waters.

1999 - A single zebra mussel found in Missouri River at Sioux City, Iowa.

1998 - First zebra mussels found in Connecticut.

1997 - New infestations of zebra mussels found in the Monongahela River and upper Ohio River, all in Pennsylvania. Heavy infestations in the Arkansas River. Population density increased slightly in the Tennessee River.

1996 - Population densities still increasing in the upper Mississippi River.

1995 - Expanding range to include nearly all of Lake Champlain. Population densities still increasing in the lower Mississippi River.

1994 - First seen in the Allegheny River in Pennsylvania. Zebra mussels occurred at nearly every lock and dam on the Mississippi River. Also starting to see small lakes with infestations in the Great Lakes states.

1993 - Zebra mussels found near New Orleans and moved up the Arkansas River in eastern Oklahoma. First appearance in Lake Champlain in Vermont.

1992 - Zebra mussels could be found nearly the entire length of the Mississippi, Ohio, and Tennessee rivers. Also present in the lower Arkansas River in Arkansas.

1991 - Zebra mussels escaped the Great Lakes by way of man-made canals into the Illinois River and subsequently the Mississippi River. Further to the East, the Erie Canal allowed zebra mussels access to the Hudson River in New York.

1990 - Zebra mussels continued to spread in Great Lakes, especially Lake Erie and Lake Ontario.

1989 - Just one year later, zebra mussels were found in all 5 Great Lakes.

1988 - Zebra mussels were first collected in Lake St. Clair, soon followed by Lake Erie.

1987 - Zebra mussel were discovered in a Lake Erie water treatment plant in Ontario, Canada.

1986 - Zebra mussels were first found on natural gas wellheads in Canadian waters of Lake Erie.